The present disclosure generally relates to the field of biomedical thermometers, and more particularly, to a tympanic thermometer that includes a sensor having a nozzle disposed therewith that improves accuracy of temperature measurement.
Medical thermometers are typically employed to facilitate the prevention, diagnosis and treatment of diseases, body ailments, etc. for humans and other animals, as is known. Doctors, nurses, parents, care providers, etc. utilize thermometers to measure a subject's body temperature for detecting a fever, monitoring the subject's body temperature, etc. An accurate reading of a subject's body temperature is required for effective use and should be taken from the internal or core temperature of a subject's body. Several thermometer devices are known for measuring a subject's body temperature, such as, for example, glass, electronic, ear (tympanic).
Glass thermometers, however, are very slow in making measurements, typically requiring several minutes to determine body temperature. This can result in discomfort to the subject, and may be very troublesome when taking the temperature of a small child or an invalid. Further, glass thermometers are susceptible to error and are typically accurate only to within a degree.
Electronic thermometers minimize measurement time and improve accuracy over glass thermometers. Electronic thermometers, however, still require approximately thirty (30) seconds before an accurate reading can be taken and may cause discomfort in placement as the device must be inserted into the subject's mouth, rectum or axilla.
Tympanic thermometers are generally considered by the medical community to be superior for taking a subject's temperature. Tympanic thermometers provide rapid and accurate readings of core temperature, overcoming the disadvantages associated with other types of thermometers. Tympanic thermometers measure temperature by sensing infrared emissions from the tympanic membrane (eardrum) in the external ear canal. The temperature of the tympanic membrane accurately represents the body's core temperature. Further, measuring temperature in this manner only requires a few seconds.
Known tympanic thermometers typically include a probe containing a heat sensor such as a thermopile, a pyroelectric heat sensor, etc. During use, the heat sensor is generally located outside the eardrum and utilizes a waveguide of radiant heat to transfer heat energy from the eardrum to the sensor. See, for example, U.S. Pat. Nos. 6,179,785, 6,186,959, and 5,820,264. These types of heat sensors are particularly sensitive to the eardrum's radiant heat energy.
In operation, a tympanic thermometer is prepared for use and a probe cover is mounted onto a sensing probe extending from a distal portion of the thermometer. The probe covers are hygienic to provide a sanitary barrier and are disposable after use. A practitioner or other care provider inserts a portion of the probe having the probe cover mounted thereon within a subject's outer ear canal to sense the infrared emissions from the tympanic membrane. The infrared light emitted from the tympanic membrane passes through a window of the probe cover and is directed to the sensing probe by a waveguide. The window is typically a transparent portion of the probe cover and has a wavelength in the far infrared range. The probe cover should provide for the easy and comfortable insertion of the probe into the ear canal.
The practitioner presses a button or similar device to cause the thermometer to take a temperature measurement. The microelectronics process electrical signals provided by the heat sensor to determine eardrum temperature and render a temperature measurement in a few seconds or less. The probe is removed from the ear canal and the probe cover is removed and discarded.
Many tympanic thermometers measure radiation being emitted from an object, such as the tympanic membrane, by employing a thermopile sensor. A membrane inside the thermopile sensor absorbs incoming radiation, which raises the temperature of the membrane. The hot junctions of thermocouples, which may be very small, are placed onto the membrane while the cold junction is thermally connected to a sensor body of the thermopile sensor. The thermocouples output a voltage change that is proportional to the temperature change between the hot and cold junctions of the thermocouple. This voltage change can be correlated to the Stefan-Boltzmann law for emitted radiation from a black body (represented in formulaic, Vout=K(eT4obj−T4sens)).
Errors in temperature readings taken by known tympanic thermometers often occur because the temperature of the sensor body is changing due to changing ambient temperature situations. These changing ambient temperature situations include other factors that affect the temperature of the thermopile sensor. For example, when a tympanic thermometer at room temperature is placed in the human ear, heat transfers to the thermopile sensor and other portions of the tympanic thermometer. The thermopile sensor includes sensor optics and a sensor can. The sensor optics and can temperature are caused to increase very rapidly and thus emit radiation back to the membrane inside the thermopile sensor. Since the temperature of the sensor is measured back at the proximal end of the thermopile sensor, Tsens will not reflect the actual temperature of the thermopile sensor and therefore an error will be introduced to the temperature measurement.
Transferring some known tympanic thermometers from a room temperature setting to a different temperature setting in the human ear is a changing ambient environment. In these types of changing ambient environments, data from thermal analysis and lab testing has shown temperature changes across the thermopile sensor can range as high as 1.5-2.5 degrees Celsius using known nozzle configurations that are disposed with the sensors of these tympanic thermometers. Devices of this kind may disadvantageously take inaccurate temperature readings resulting in drawbacks for treating and diagnosing patients.
Therefore, it would be desirable to overcome the disadvantages and drawbacks of the prior art with a tympanic thermometer that includes a sensor having a nozzle disposed therewith that improves accuracy of temperature measurement. It is contemplated that the tympanic thermometer and its constituent parts are easily and efficiently manufactured and assembled.